Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual é a data, quando a equipe visitante é "Brentford"?
 ###Tabelas: CREATE TABLE sonshine_radio_stations_in_the_philippines (sonshine_radio_stations_in_the_philippines_id AUTO_INCREMENT PRIMARY KEY, Branding VARCHAR, Callsign VARCHAR, Frequency VARCHAR, Power (kW) VARCHAR, Location VARCHAR) CREATE TABLE all-time_ranking_in_the_championship_playoff_since_the_introduction_of_the_playoff_system_in_2009 (all-time_ranking_in_the_championship_playoff_since_the_introduction_of_the_playoff_system_in_2009_id AUTO_INCREMENT PRIMARY KEY, Rank INT, Club VARCHAR, Seasons INT, Played INT, Drew INT, Lost INT, Points INT, Avg. Points INT, Goals for INT, Goals against INT, Goal diff INT) CREATE TABLE singles_champions (singles_champions_id AUTO_INCREMENT PRIMARY KEY, Year INT, Name of Tournament VARCHAR, Champions VARCHAR, Runners-up VARCHAR, Score VARCHAR) CREATE TABLE wins_17–13 (wins_17–13_id AUTO_INCREMENT PRIMARY KEY, Outcome VARCHAR, Date VARCHAR, Championship VARCHAR, Surface VARCHAR, Opponent in the final VARCHAR, Score in the final VARCHAR) CREATE TABLE sixth_round_proper (sixth_round_proper_id AUTO_INCREMENT PRIMARY KEY, Tie no VARCHAR, Home team VARCHAR, Score VARCHAR, Away team VARCHAR, Date VARCHAR)  
SELECT Date FROM sixth_round_proper WHERE Away team = brentford